Quarterly report pursuant to Section 13 or 15(d)

Revenue from Contracts with Customers - Summary of Future Obligations (Details)

v3.8.0.1
Revenue from Contracts with Customers - Summary of Future Obligations (Details)
$ in Thousands
 3 Months Ended
Mar. 31, 2018
USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-04-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Deferred revenue $ 965
Revenue, remaining performance obligation, expected timing of satisfaction, period 9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Deferred revenue $ 324
Revenue, remaining performance obligation, expected timing of satisfaction, period 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Deferred revenue $ 239
Revenue, remaining performance obligation, expected timing of satisfaction, period 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Deferred revenue $ 2,109
Revenue, remaining performance obligation, expected timing of satisfaction, period